The invention relates to a motor vehicle equipment assembly, of the type comprising: an air bag support; an air bag fixed to the support by first fixing means, the air bag having a rest configuration and a deployed configuration; a force spreader plate for spreading the impact force from a passenger over the air bag, said plate having a visible surface forming a portion of the facade of the equipment in the mounted state; and frangible fixing means fixing said plate relative to the support when the air bag is in its rest configuration, which means are broken under the force for deploying the air bag.
The invention applies in particular to air bags for protecting the knees of passengers in motor vehicles.
In the state of the art, e.g. document U.S. Pat. No. 6,131 950, an air bag assembly is already known for retaining the knees of passengers. That assembly comprises an air bag support, an air bag, and a force spreader plate.
The air bag has an open end which is fixed to the support and it has a closed end. The closed end of the air bag is fixed along the edge of the force spreader plate and the air bag bears against the rear surface of the plate. For this purpose, a wire frame is inserted in the air bag, which frame matches the outline of the edge of the plate. The edge of the force spreader plate is folded over the frame, thereby crimping the air bag.
That assembly is difficult to manufacture because of its numerous parts and it requires a large quantity of material.
An object of the invention is to mitigate those drawbacks and to provide low cost air bag equipment for a motor vehicle, the equipment including a rigid force spreader element.
To this end, the invention provides an assembly of the above-specified type, wherein the air bag comprises the force spreader plate and a sheath of substantially closed cross-section, wherein the sheath has a first end fixed to the support by said first fixing means and a second end, and wherein the sheath is fixed to the force spreader plate along said second end by second fixing means in such a manner that the inside volume of the air bag is defined in its portion close to the second end of the sheath by the sheath and by the force spreader plate secured to the sheath.
In particular embodiments, the assembly of the invention further comprises one or more of the following characteristics:
said first and/or second fixing means comprise clamping means for clamping the sheath against said plate and/or against said support;
the clamping means comprise:
openings formed in said respective first or second end of the sheath;
studs placed on the plate and/or the support and extending through the openings; and
members co-operating with the studs and clamping the corresponding end of the sheath against the surface of the plate or of the support respectively;
said first and/or second fixing means comprise a portion of the support and/or of the plate molded onto said respective first or second end of the sheath;
said first and/or second fixing means comprise said respective first or second ends of the sheath fixed to the support and/or to the plate by heat-sealing;
the assembly has elastic zones for damping the stresses applied to the plate during deployment of the air bag;
the cross-section of the sheath in the deployed state is substantially constant;
the assembly comprises supplementary impact damping means adapted to damp a second impact of the passenger against the air bag;
the assembly further comprises supplementary means for retaining and guiding the force spreader plate during deployment of the air bag, and these means comprise reinforced portions of the sheath, in particular portions that are formed integrally therewith, said portions extending from said first end to said second end and being fixed firstly to the plate and secondly to the support; and
the support is a lining of a door for being hinged to a piece of motor vehicle equipment, and the plate is at least a portion of the visible surface of the door.